All of this isn't exactly the issue. I am not sure off hand if he does or does not claim that it is 100% built in the USA. I am pretty sure that the plaque inside the car even says that it is handcrafted in Silverstone, England
I would be worried if it were built in China rather than England.
Also, what is wrong with having someone else do what they do best to make the product better? If I knew how to make engines and power, but no clue about bodywork or aerodynamics, I would much rather contract that out to get it done right.